One would assume that every building culture, after a variety of attempts at building tall stuff that collapsed, would eventually hit upon the pyramid as the most stable way to build high. Heck, all they had to do is look at a pile of dirt or sand to figure it out. You're right, there's no big mystery behind the concept of a pyramid.
"One would assume that every building culture, after a variety of attempts at building tall stuff that collapsed,"
Some early Egyptian pyramids did collapse. I think one of the pyramids at Giza is called "the collapsed pyramid". Looks like it's builders got halfway done and realized it wasnt going to work and had to rework the angle.